Selective relay.



E. R. BRODTUN.

SELEGTIVE RELAY.

APPLIUATION FILED AUG. 2a, 1909.

Patented' Apr.4 22, 1913.

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E. R. BRODTON.

SBLECTIVB RELAY.

APPLIGATION FILED AUG. ze, 1909.

A Patented Apr. 22, 1913.

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ED'WARD R. BRODTON, 0F MOBILE, ALABAMA, ASSIGNOR TO MODERN ELECTRIC APPLIANCE COMPANY, OF MOBILE, ALABAMA.

SELECTIVE RELAY.

Specification of Letters Patent.

Patented Apr. 22, 1913.

Application filed August 28, 1909. Serial No. 515,080.

To all whom t may concern Be it known that I, EDWARD R. Bnon'roN, a citizen of the United States, residing at Mobile, in the county of Mobile and State of Alabama, have invented a new and useful Selective Relay, of which the following is a specification.

This invention has reference to selective relays and its object is to produce a relay of the electro-magnetic type wherein the continuity of the circuit where more than one relay is used is established by the relays in succession up to the relay designed to respond actively to produce a signal or other useful work.

The invention is furthermore designed to provide a relay structure wherein each relay up to the active relay successively establishes the circuit and then maintains the circuit by the action of current from sources local to the energized portion of the relay and these local sources are controlled bya master relay receiving current from the main source and operating to restore the entire system to normal condition on the breaking of the main circuit. Each relay of the series is designed to control a circuit capable of performing useful work in the form of signals, mechanical work, and the like, but when the controlling side of the relay is operative then the local circuit is rendered inactive and unresponsive to line current up to the selected relay when the line current becomes receptive to the controlling means for the local circuit to render the latter active.

Provision is likewise made for preventing two or more local circuits becoming active from the accidental closing of two sending devices so that a false or double signal is avoided.

Provision is also made by the present invention for preventing the accidental closing of the relay circuit from shocks or ars or other extraneous causes, especially where such conditions are liable to be present and where the closing of the `circuit unintentionally at the receiving station, as by accidental means there present, would be destructive. 1

The invention will be best understood from a consideration of the following detailed description taken in connection with the accompanying drawings forming a part of this specification, in which drawings,

Figure l is a diagrammatic representation of a system embodying the present invention in one of its forms. Fig. 2 is a diagram illustrating the manner of prevent,- ing the action of the local circuits at two stations should two armatures be moved to the circuit closing position at one time. Fig. 3 is a diagram showing a more compact disposition of the parts than in the showing of Fig. l. Fig. 4 is a diagram illustrating an embodiment of the invention for use where the structure is liable to the effect of shocks and jars. Fig. 5 is a view of a detail of the structure of Fig. 4. Fig. 6 is a view of another detail of the structure of Fig. 4.

.Referring at first to Fig. l there are shown two receiving stations A-B, it being understood however that there may be any desired number of receiving stations, and these two stations are to be taken simply as indicative of a system. There is also shown a transmitting station C which' may be distant from the receiving station or for some purposes may be quite closeto the receiving station, or the receiving stations may be grouped into a small area for the selective operation of closely associated mechanical structures, such, Yfor instance, as the type levers of a typewriter. Again the invention may be utilized for signaling purposes where it is desirable to employP but one set of main line wires or conductors and in this case the extent of territory covered by the system may be quite limited, as, for instance, on ship-board or in a fort or in a building, or again, it may extend over a wide area where it is desired to transmit selectively signals or `messages from one point to another. At the transmitting station there is -located a battery l, which may be taken as indicative of any suitable source of electric energy and 'from one side of this battery there extends a main line conductor 2 whichA may include a rheostat 3 of any suitable type for maintaining the current upon the line under changing conditions due to weather and other causes. There is also anotherline conduct-or 4, and from this conductor and the transmitting station there are branched ofi' other conductors 5 terminating in contacts 6. Connected to the side of the battery l remote from the conductor 2 isianother conduct-or 7 to which are connected in multiple switch keys or levers 8 so arranged and connected to the conductor 11.

as to each have in its pat-h a contact terminal 6. Between the levers 8 are introduced resistances 9. By this means an operator may send currents to the line from the battery 1 but of strength depending on the number of resistances 9 included in the circuit. Branched off from the main line conductors 2 and 4 at each station are conductors 10-11, the conductor 10 branching off from the conductor 2 and the conductor 11"'branching off from conductor 4. Conductor 10 is connected to one side of an electro-magnet 12 which may be a standard electro-magnet of the ironclad type, although this is by no means necessary, and the same conductor 10 is also connected to one side of an electro-magnet 13, by a branch conductor 14. The other side of the magnet 12 is'connected to a conductor 15 leading to a contact terminal 16 in the path of a contact finger 17 having a normal tendency toward the said Contact terminal 16 and this finger 17 isv connected to a conductor 18, leading The other side of the magnet 13 from that connected to the conductor 14 is connected by a conductor 1-9 to the said conductor 11. The magnet 12 is'provided with an armature 20shown in F ig. 1 as pivoted to the magn'e't structure and normally constrained by an adjustable spring 21. The magnet 13 is provided with an armature 22 shown in Fig.` 1 as pivoted to the structure of the magnet 13, and normally constrained by an adjustable spring 23. The armature 20 has an extension in the path of which toward the magnet is a circuit terminal 24 preferably of the yielding type, and this circuit forms the terminal of a conductor 25 to 'which reference will hereinafter be made.

.The armature 20 is either of conducting material throughout or has a special conducting strip applied thereto and this strip irs connected by a conductor 26 to the conductor 15 before referred to. At the free end of the armature 20 there are insulating pins 27-28, the pin 27 being adapted to engage the spring finger 17 when the armature isattracted by the magnet and in the path of the pin 28 there is a spring finger 29 adapted to make contact with the terminal 30 When the armature 2O is atarmature is attracted by the magnet is a circuit terminal at the end of a conductor 36 leading to a battery 37 or other suitable source of current and this battery is connected on the side opposite to that to which the conductor 36 is connected, to a bell 38, which may be taken as indicative of any signal device or other electro-mechanical means, such, for instance, as the type lever of a typewriter. One side of the magnet 31 is connected to the conductor 10 by another conductor 39 While the other side of the magnet is lconnected by a conductor 40 to an adjustable backstop 41 in the path of the armature 20.

Let it be assumed that there is produced upon the line conductors 2 and 4 an electrical impulse of suitable strength, then the magnet 31 at station A Will be energized, the circuit being established from the bat tery 1 to the rheostat 3 and conductor 2 to the conductor 10 thence by' conductor 39 to the magnet 31, thence by conductor 40 to the back-stop'screw 41, thence by the armature 20 which is normally in contact With the back-stop 41, thence by the conductor 26 to the conductor 15, thence to the circuit terminal 16 and spring finger' 17, thence by the conductor 18 to the conductor 11, and back to the conductor 4 and through the key 8 which has been depressed for the purpose back to the battery 1. This Will cause the attraction of the armature 32 thus establishing a circuit from the battery 37 to the bell 38, thence from the latter which is connected to the armature 32 by a conducto-r 42 to said armature and from the latter to the contact 35, thence by the conductor 36 back to the battery thus energizing the bell and causing it to emita signal. If the bell be replaced by any other electro-mechanical device responsive to the current furnished by the battery 37 then such device will be actuated for a time agreeable to the time of the closing of the circuit by the depressing of a key 8 against a cont-act terminal 6. If however, the current transmitted to line be such as to cause the actuation of the magnet 12 to attract its armature 20, then before the magnet 31 can act the circuit of this magnet is broken by the attraction of the armature 20 moving the said armature away from the backstop 41. Current sufficient to energize the magnet 12 at station A also causes the energization of the magnet 13 at the same station and the attraction of its armature 22. The armature 22 is connected to one end of a conductor 43 and this conductor extends from station to station and is connected at each station by a branch conductor 44 to the battery 37, preferably at' an intermediate point. The other side of the battery, namely that connected to the conductor 36 is connected by a branch conH ductor 45 to the conductor 25. Theenergization of the magnet 13 therefore establishes a circuit from the battery 37 to the conductor 44 to the conductor 43 thence to the armature 22 and from the latter to the magnet 12 on one side of the said magnet by Way of a conductor 46 having a terminal 47 in the path of the armature 22 and from the magnetl 12 the circuit is established by Way of the conductor 26 to the armature 20 which has been attracted by the energization of the magnet 12, thence by the Contact 24 to the conductor 25 and by Way of the conductor 45 back to the battery 37. The energization of the magnet 12 and the attraction of its armature 20 has caused the rupture of the circuit formerly established through the conductors 15 and 18 at. the contact 16 and the spring finger 17 which latter is moved away from the contact 16 by the pin 27 on the movement of the armature 20 toward the magnet 12. Now the magnet 12 is maintained energized solely by the local source 37 and is cut out from the line current so that the latter may be employed for other purposes and this magnet remains so energized until'the line current ceases and the magnet 13 becomes denergized thus breaking the local circuit at the contact 47 and permitting the armature 20 to return to its normal position under the action of the spring 21. The energization of the magnet 12 has, as before stated, completed the circuit to the main line conductor at the spring finger 29 and terminal 30 so that the main line current now finds a path beyond station A and toward station B. By use of the telegraphic keys 8 and the vary ing resistances 9, it is evident that currents of varying strength ma \,T be caused to excite the main line and thereby actuate the various selective relays which are so Wound as to be of a different selectivity from one another. 1f it be assumed that the current causing the initial energization of the magnet 12 be sufficient to energize the magnet 31 at station B then a signal will be there produced, but if this current be of such character as to energize the magnet 12 at station B then the magnet 31 there located will be cut out of circuit and the continuity of the line conductor 4 Will be continued beyond the station B to a succeeding station or stations but since the magnet 13 at station A remains energized or becomes energized by any current established on the linc sufficient to energize the magnet 12 at station A and will be energized by any current designed to energize any of the magnets 12, each succeeding magnet'12 will be energized by the local source 37 at its station.

The circuit controlling each succeeding magnet12 is as follows: the armature 20, at station B', the contact 24, the conductors 25 and 45, the batteries 37 at station B,

the conductors 44 and 43, the armature 22 of the magnet 13 of the station A, the contact 47, the conductor 46, the coil of magnet 12 of station A, t-he conductor 26, the armature 2O of the magnet 12 of the sta-V tion A, the contact 24, and the conductor 25 of station A, through the branch conductor 46 at station B, to the coil of the magnet 26 and back to the armature 2O of the magnet 12 of station B.

As an example of the operation of the structure shown in Fig. 1 let it be assumed that it is desirable to produce a signal or other effect at the tenth station. The circuit is established at the proper key 8 and the current sent to line will cause the energization of the magnets 12 and 13 at the first station thus completing the main line circuit at this point and cutting the magnet 12 into the local energizing circuit while the line current passes on to the second sta tion causing the energization of the magnet 12 there located and its automatic inclusion in the circuit of the local battery at the second station With the establishment of the main line circuit to the third station, and so on up to the tenth station where the magnet 31 vyill respond since the magnet 12 at this tenth station will not respond to the current reaching it. Thus at the tenth station the signal or other effect is produced.

' There are numerous Ways of making the magnets 12 respond only to the desired current, but the preferable Way is to make the magnets 12 all alike and also to make all the other magnets alike and then to introduce a suitable resistance 48 in one of the branch conductors leading into the station, say branch conductor 11, these resistances varying in accordance with the desired effect and the current sent to lin-e being of commensurate strength.

There are conditions under Which there is a liability of closing the circuit at two of the armatures 32 at the same time and this might tend to cause the closure of two of the local circuits and thereby produce confusion. To meet such a contingency, the arrangement illustrated in Fig. 2 may be employed. In this case the armature 32 of each magnet 31 is coupled up by a conductor 42 to one side of a battery 37 While the other side of this battery is connected to the bell 38 or other such device by a conductor 49. The other side is connected by a conductor 50 to a circuit terminal 51 in the path of the armature 32. All the contacts 51 are connected in multiple by conductors 52 and all the batteries 37 are connected in series by conductors 57. Let it be supposed that any one of the magnets 31 is energized and armature 32 is attracted and a circuit is completed from the battery 37 by the conductor 42 to t-he armature 32 thence by contact 51 and conductor 50 to the bell 38 thence by conductor 49 back to the battery 37". The bell will then ring or the other devices will be operated as the case may be. Let it be supposed that two of the magnets 31 are energized at the same time and their armatures attracted. This may occur from a variety of causes either accidental or malicious, or the armatures may even be depressed without the magnet being energized,vas by shock or jar or by accident or malicious intent, then the circuit will be established as follows, assuming, say, that the first and third of the magnets 31 are energized or their armatures are closed down on the contact 51. Starting from the first battery 37 the circuit will follow the conductor 42, leading from this battery, thence through the armature 32 to the contact 51 thence by the conductor 52 to the contact 51 engaged by the armature of the third magnet thence by said armature to the conductor 42 connected thereto, thence to the conductor 57 and back through the batteries 37 coupled up, by the conductors 57, there being two such batteries in the circuit. This gives a low resistance path for the current and it will traverse such path in preference to passing through the bells which are of much higher resistance so that the bells are shunted and become therefore inoperative. Other armatures may be closed, but it will be found that the bells of like devices are always shunted by a low resistance circuit when more than one armature is closed on its contact 51.

In F 3 there is shown a somewhat more compact form of the structure of Fig. 1, especially the arrangement of station A,than is shown in said ligure. In the structure of Fig. 3 there is provided a suitable base58 and on this base are mounted the magnets 12, 13, and 31. The armatures of these magnets are somewhat differently arranged than in the showing of Fig. l, but otherwise the electrical circuits are similar except that the j bells o-r other translating device receive the actuating' current directly from the main line conductors. In order to condense the space occupied by the struct-ure of F 3 each armature 20, 22, or 32 as the case may be has a spring 59 interposed between it and the head of the magnet. This spring may have its tension adjusted by a suitable set screw 60 and the extent of movement of the magnet actively is determined by a stop screw 61 carried. by the magnet head. Fast to each armature, but insulated therefrom is an arm 62 so bent as to normally lie lengthwise of the magnet. Then the armature is attracted then the free end of the arm 62 is moved in a direction to complete or break the circuit. at the contact as in the-structure of Fig. 1. There are some modifications of the circuit connection over the showing of Fig. 1., For inst-ance the bell 38 is con'- nected on one side by a conductor 64 to the main line conductor 2 and on the other side by the conductor 65 to the contact 35 m the 'path of the arm 62 carried by the armature 32. This arm 62 is connected by a conductor 66 to the main line conductor 4 and by a conductor 67 to the bell circuit of succeeding stations. Since the energizing source for the bells 38 is the current on the main line conductor, a separate current source 68 is provided for the energization of the magnets 12 when they have been cut out from their connection with the main line conductors. This current source, shown as a battery, is coupled with two conductors 69 and 70 extending to the several stations. From the conductor 69 at the iirst station there is a conductor 71 leading to the arm 62 of the armature 22 and from the conductor 70 there leads a conductor 72 to the contact 24 so that when the magnets 12 and 13 are both energized there is established a circuit from the battery 68 by the conductor 69to the conductor 71 thence by the arm 62 tothe conductor 46 and by the included portion of the conductor 10 to o-ne side of the magnet- 12, thence by the conductor 26 to the arm 62 carried by the armature 20, thence to the contact 24 and by the conductor 72 to the conductor and back to the battery 68, thus maintaining the magnet 12 energized when it has cut itself out from connect-ion with the main line conductors 2 and 4.

The system of Fig. 4 is designed more particularly for use where the apparatus is subjected to violent shocks or jars lia-ble to i cause the accidental closure of the circuit.

There are certain features of the invention, particularly as disclosed with reference to the showing of Fig. 4, which are useful in connection with the transmission of signals or intelligence on war vessels or in forts where the structure is liable to shocks and jars caused by the explosion of large guns. The system of Fig. 4 is also useful in other connections and especially in connection with the firing of any explosive such as in blasting and under like conditions.

In the showing of Fig. 4 the line conductors 2 and 4 are indicated as in the other figures and the sending station C is assumed to be the same as in Fig. 1, though not illustrated in Fig. 4. Furthermore Fig. 4 shows the structure of station B only, while that of station A has been omitted, but when the showing of Fig. 4 is designed for the selective transmission of signals or intelligence it will be understood that it will include a station like station A of Fig. 1 but modiied in accordance with the showing of Fig. 4.'

In place of the several magnets and their armatures, the system of Fig. 4 includes electric motors, these motors being indicated at 723-474, one of the motors being also shown in Fig'. 6i These motors are preferably though not necessarily of the permanent field type, the field magnet being shown at 75 in Fig. (3 and the armature at 76 in the same figure. No commutator is employed and the armature is designed to make but a partial revolution when energized. Of course the armature may be in the form of a permanent magnet and the field may be wound, but these are matters of design and are of course included in the invention. At one end of the armature shaft of each motor there is a cam disk 77, and at the other end of the armature shaft is a pin or arm 78 to which is connected one end of a spring 79, the other end of which is coupled to an adjusting arbor 80 by means of which the tension of the spring 79 may be regulated at w`ill. In the pathof the cam disk 77 of the motor 73 is a finger 81 having a normal tendency toward a contact 82 but yielding to move away from the contact under the action of the cam 77 carried by the motor 73. In the path of the cam disk 77 carried by the armatureshaftl of the motor 74 is a contact finger 83 in the path of which is a contact terminal 84, but thev contact finger 83 has a normal tendency to move away from the contact terminal v84 and is moved toward .the contact terminal 84 by the action of the cam` disk of the said motor 74. On one face of the disk 77 of the motor 74 there is an insulating boss 85 in the path of which is a contact finger 86 having a normal tendency to move away from a contact terminal 87 in its path, but the boss 85 is so shaped as to move the contact finger 86 into engagement with the contact 87 when the disk 77 of the motor 74 is ro, tated to cause the movement of the finger 83 into engagement with the contact 84. The main line conductor 2 has branched therefrom a conductor 88 leading to the armature 76 of the motor 74 and also branched ofi' by a conductor 89 to the armature 76 of the motor 73. The main line conductor 4 is connected by a branch conductor 90 wit-h the finger 81 and by a continuation 91 with the other Vside of the armature 76 of the motor 73. `The Contact 82 in the path of the finger 81 is connected by a conductor 92 with the side of the armature 76 of the motor 74 opposite that connected to the conductor 88. Also branched off from the conductors 2 and 4 are other conductors 93 and 94 respectively. The conductor 93 is coupled to one side of a rheotome 95, the other side of which is coupled to the primary winding of an induction coil 96, the other side of which is connected by a conductor 97 to the contact finger 83. The conductor 94 is coupled to the contact terminal 84 in the path of the finger 83. The secondary winding of the induction coil 1s connected at its opposite ends to conductors 98 and 99 respectively leading to any suitable point of utilization.` One use of the current generated in the conductors 98 and 99 is illust-rated in Fig. 4 where these conductors have connected to them branch conductors 100 and 101 leading respectively to the contact terminal 87 and to a spark gap 102, the other side of which latter is connected by a conductor 103 to the contact finger86. n

The particular showing of Fig. 4 is designed for use for the firing of explosives by high tension electric current producing a spark at the spark gap 102, but it will be observed that at leasttwo circuits mustbe closed simultaneously and at the same time current must be present on the main line before the spark will be produced. This reduces to a negligible minimum the liability of a premature explosion. Furthermore by making the motor 73 responsive to a predetermined current, any excess current on the line conductors 2 and 4 will out out the motor 74 and so prevent the generation of the high tension active current.

Let it be assumed that there is produced upon the main line conductors 2 and 4 a proper current impulse or impulses, then the current will follow the conductor 88, traverse the armature 76 of the motor 74 and return by way of the conductor 92, contact 82, finger 81, conductor 90, to the other main line conductor 4. This will cause an establishing of electrical conditions in the motor 74 which will cause a partial rotation of the armature against the action of the spring 79 and sufiicient to bring theV cam portion of the disk 77 against the finger. 83 thus closing the same on the contact 84 and simultaneously with its movement the boss 85 is brought into engagement with the finger 86 and the latter is moved into contact with the terminal 87. There is now established a circuit from the conductor 2 by way of the conductor 93 to the rheotome 95, thence through the primary of the induction coil 96 and by the conductor 97 to the finger 83 thence by the contact 84 and conductor 94 to the main line conductor 4. At the same time there is established a circuit through the secondary lwinding of the induction coil 96 by way of the conductor 100 to the contact 87 thence by the finger 86 to the conductor 103 and through the s ark gap 102 and by the conductor 101 bac to the secondary winding of the induction coil 96. The rheotome 95 immediately begins to act and there is produced in the secondary .circuit a series of high tensio-n impulses which will cause a spark at the spark gap 102 and the firing of the explosive in which this portion of the circuit is assumed to be embedded in the usual manner. Suppose however that a current traverses the line sufficient to operate the motor 73, the circuit therethrough being normally closed by way of the conductor 88, branch conductor 89 conductor 91, andl 90 back to the main line l conductor 4. Before the current can actively operate the motor 74 the motor 73 has respondedland the disk 77 has caused the opening of the circuit of the motor 74 by moving the contact finger 8l away from the contact 82. Consequently there is no establishment or' the circuit through the induction coil 96, and the latter therefore remains inert.

lt will be understood that motors like the motors 7 3 and 74 may replace any or all of the magnets of the systems of Figs. l and 8 and in structures where it is desirable to avoid the effect-s of shocks or jars which might accidentally cause the closure of the circuit, a double brake like that shown in connection wtih thc Amotor 74 may be employed to reduce the liability of the closure of the circuit. In the structure of Fig. 4 it will be noted that the disk 77 controlled by the motor 74 closes two circuits at right angles one with the other at the point of closure thus still further reducing 'the liability `of accidental closure from shocks or jars. Furthermore a motor having the stator or the rotor in the form of a permanent magnet with the Vother member polarized either permanently or by the action of the permanent magnet present and the normal effect of the permanent mag net 'co-acting with the spring 79, the

structure will resist displacement under shocks or jars because of the magnetic conditions. Furthermore the disturbance of a rotatable member biased either magnetically vor by a spring or both, by shocks or jars is practically an impossibility so that the structure of Fig. 4 is particularly useful for signal systems or intelligence systems or other uses upon War vessels or in forts or in 'any localities Where there is a likelihood of a 'disturbance from heavy shocks or jars.

Where the transmission line is long or under other circumstances it is desirable that the relays should be especially sensitive, the armatures may be polarized.

lt will be understood of course that the single magnets shown may be replaced by horse-shoe magnets and that where desired or preferable alternating current may be used instead of direct or constant current. Also a ground return may be used instead of an all metal circuit. Then motors such as are shown in Fig. 4 are used that portion of the motors which is permanently magnetic may have a coil thereon, to strengthen vthe magnets when there is current on the line or electromagnets may be used instead of permanent magnets.

What is claimed is:

l. .In a selective electric relay system, a transmitting station having a plurality of selecting devices, and a source of electrical energy; two line conductors connected to said devices and the source; and a receiving station; a normally closed bridge connection at the receiving station and with both line conductors; a relay at the receiving station having its coil in said bridged connection and its armature disposed to open said bridged connection when the relay is energized; a signaling relay at the receiving station connected to the line conductors through a shunt with the bridge connection around the coil of the first relay and including the armature of the irst relay when unattracted; a translating circuit controlled by the armature of the signaling relay and including a source of electrical energy, a translating device and the armature of the signaling relay; a holding circuit for the first mentioned relay including the last source of electrical energy and the coil of the relay; and a relay whose coil is also in the bridge connection to the line for closing the holding' circuit.

2. In a selective electric relay system, a transmitting station having a plurality of selecting devices, and a source of electrical energy; two line conductors including said devices and the source; and a receiving station; a normally closed bridge connection at the receiving station and with both line conductors; a relay at the receiving station having its coil in said bridged connection and its armature disposed to open said bridged connection when the relay is energized; a holding circuit for said relay; a signaling relay connected to the line conductors through a shunt with the bridge connection around the coil of the first relay at the re- ,vceiving station and including the armature of the first relay when unattracted; a translating circuit controlled by the armature of the signaling relay and including a source of electrical energy, a translating device and the armature of the signaling relay; and a relay closing said holding circuit for the irst relay to ret-ain the first relay energized after the circuit therethrough from the main line is broken.

l 3. In a selective relay system, a transmitting and two or more receiving stations; a source of electrical energy at the transmitting station; line conductors connected to said source and extending to connect the receiving stations; a normallyT open switch in one line conductor at each receiving station, a plurality of selecting' devices connected to the line conductors at the transmitting station; a relay in each receiving station for closing its respective switch; a normally closed bridged connection connected to both line conductors at each receiving station and including its respective switch controlling relay; a signaling relay in each receiving station connected to both line conductors through a connection to the bridge connection and around t-he coil of the switch Controlling relay and including the armature of said switch controlling relay when unattracted; a translating circuit including a source of electrical energy, a translating device and the armature of the signaling relay at each receiving station, a relay in the receiving station for actuating one or more switch controlling relays of the system, and a circuit including one source of electrical energy of a translating circuit, the armature of the last relay and the coil of the switch controlling relay to cause the energization of the switch controlling relay When the said last relay is energized.

In testimony that I claim the foregoing as 15 my own, I have hereto affixed my signature in the presence of tWo Witnesses.

EDWARD R. BRODTON.

Witnesses:

E. HUME TALBERT, F. T. CHAPMAN.

Copies of this patent may be obtained for ve cents each, by addressing the Commissioner of latente.

Washington, D. C. 

